Sheetrock® Brand Mold Tough® Panels Firecode® X are Type X panels that feature a noncombustible, moisture-resistant gypsum core that is encased in moisture-and mold-resistant, 100% recycled green face and brown back papers. The face paper is folded around the long edges to reinforce and protect the core, and the ends are cut square and even. The long edges of the panels are tapered, allowing joints to be reinforced and concealed with Sheetrock® Brand joint treatment systems.